Sorsby's fundus dystrophy: a case report of 24 years follow-up with electrodiagnostic tests and indocyanine green angiography

Purpose Five families with dominantly inherited macular dystrophy were orig inally described by Sorsby et al. in 1949. Key features include early bilat eral central visual loss secondary to either choroidal neovascularisation o r central geographical atrophy and late progressive chorioretinal atrophy. We report a member of one of the original families who has been studied wit h a series of investigations over a long time, providing important informat ion on differences in the phenotype and natural history of a rare genetical ly determined macular dystrophy. Methods The patient has been followed up for the last 24 years, from asympt omatic to full manifestation of Sorsby's fundus dystrophy. Series of fundus photographs, colour vision, dark adaptation and electrodiagnostic tests we re performed. The disease was also studied with fundus fluorescein angiogra phy and indocyanine green angiography. Results Unlike her other family members, who were reported in other studies as all having rapid loss of vision secondary to disciform macular disease, our patient has a unique clinical course in that she has a progressive bil ateral central and generalised chorioretinal atrophy with a well-preserved minute central island of fovea. Nyctalopia was her early and only symptom. There was evidence of central scotoma, tritanopia and mild abnormality in d ark adaptation. Rod function was affected earlier and to a larger degree th an cone function. Conclusions The overall features suggest phenotypic variability within a fa mily in this autosomal dominant macular dystrophy. The findings from indocy anine green angiography and a consecutive series of electrodiagnostic tests in this condition support the theory of partial choroidal hypoperfusion an d an interesting progressive rod-cone dystrophy as part of the pathophysiol ogy.